i can see you

A boy named lucas finds that her classmate is missing and everyone was searching for her. Sofia disappears without a clue.Yeh,her name is Sofia. A couple of weeks later Lucas finds sofia's locket. He keeps it with him. Next day when he woked up he saw her but realised no one else could.So how was that possible?.....why lucas???
You can read the whole story to know the answers.👆